Existing techniques for bone quality assessment are based on photon and X-ray absorptiometry and X-ray quantitative computed tomography. Gramp et al. The Radiological Clinics of North America 1993 31(5):1133-1141; Faulkner et al. Am. J. Roentgenology 1991 157:1229-1237. Each of these methods are routinely used in clinical practice. However, these techniques have limited applicability because of expensive and bulky equipment and potential risk of radiation during the procedure.
The application of acoustic energy for non-invasive skeletal diagnosis has also been shown to be feasible and has advantages for bone mass and strength measurement. Jurist, J. Phys. Med. Biol. 1970 15:417-426; Orne, D. Biomechanics 1974 7:249-257; Thomson et al. Med. Biol. Eng. 1976 14:253-262; Saha, S. and Lakes, R. S., J. Biomechan. 1977 10:393-401; Doherty et al. J. Biomechan. 1974 7:559-561; Waud et al. Calcif. Tissue Int. 1992 51:415-418; Selle, W. A. and Jurist, J. M. J. Am. Geriat. Soc. 1966b 14:930. Unlike conventional radiological techniques, acoustic techniques emit no radiation, are cost effective, and utilize equipment which is portable and easy to operate. Subsonic techniques for determining the in vivo properties of bone, known as impedance and resonance methods are based on measurement of the response of a bone to a flexural wave excitation in the frequency range 200 to 1000 Hz. A correlation between the resonance frequency of the human ulna and osteoporosis has been reported. However, while a significant number of acoustic tests have been performed, these techniques have not been used as a bone diagnostic tool for clinical application because of difficulties in the interpretation of the measurements. Ultrasound velocity and attenuation depend on density as well as on certain other properties of bone. A recent report showed that only 53% of broadband ultrasound attenuation (BUA) value and 44% of velocity of sound (VOS) value can be accounted for by bone density. Waud et al. Calcif. Tissue Int. 1992 51:415-418. Interpretation of subsonic measurement of flexural vibration of bone is also a difficult task and to a great extent, depends upon a corresponding mathematical model of the test object. The effect of soft tissues creates additional difficulties in the interpretation and use of these techniques.
A non-invasive, nonhazardous and cost effective infrasound resonance method for the quantitative measurement and monitoring of bone quality has now been developed involving the measurement of the rigid body longitudinal resonance of a bone. Instrumentation for making these measurements is also provided.